1 files changed, 36 insertions, 34 deletions

diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index a2bb11d4e..d3d700c0c 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -5571,14 +5571,19 @@ static node *do_non_interpreted()
   return new non_interpreted_node(mac);
 }
 
+// In troff output, we translate the escape character to '\', but it is
+// up to the postprocessor to interpret it as such.  (This mostly
+// matters for device control commands.)
 static void encode_char_for_troff_output(macro *mac, const char c)
 {
+  bool is_char_valid = true;
+  const char *sc = 0 /* nullptr */;
   if ('\0' == c) {
-    if (tok.is_stretchable_space()
-	     || tok.is_unstretchable_space())
+    if (tok.is_space()
+	|| tok.is_stretchable_space()
+	|| tok.is_unstretchable_space())
       mac->append(' ');
     else if (tok.is_special()) {
-      const char *sc;
       if (font::use_charnames_in_special) {
 	charinfo *ci = tok.get_char(true /* required */);
 	sc = ci->get_symbol()->contents();
@@ -5612,29 +5617,32 @@ static void encode_char_for_troff_output(macro *mac, const char c)
 	    mac->append(']');
 	  }
 	  else
-	    error("special character '%1' cannot be used within a"
-	          " device control escape sequence", sc);
+	    is_char_valid = false;
 	}
 	else
-	  error("special character '%1' cannot be used within a device"
-		" control escape sequence", sc);
+	  is_char_valid = false;
       }
     }
     else if (!(tok.is_hyphen_indicator()
 	       || tok.is_dummy()
 	       || tok.is_transparent_dummy()
 	       || tok.is_zero_width_break()))
-      error("%1 is invalid within device control escape sequence",
-	    tok.description());
+      is_char_valid = false;
+    if (!is_char_valid) {
+      if (sc != 0 /* nullptr */)
+	error("special character '%1' is invalid within a device"
+	      " control command", sc);
+      else
+	error("%1 is invalid within a device control command",
+	      tok.description());
+    }
   }
   else {
-    if ((font::use_charnames_in_special) && ('\\' == c)) {
-      /*
-       * add escape escape sequence
-       */
-      mac->append(c);
+    if (c == escape_char) {
+      mac->append('\\');
     }
-    mac->append(c);
+    else
+      mac->append(c);
   }
 }
 
@@ -5678,34 +5686,28 @@ static node *do_special()
 
 static void device_request()
 {
-  // We can't use `has_arg()` here because we want to read in copy mode.
-  int c;
-  for (;;) {
-    c = input_stack::peek();
-    if (' ' == c)
-      (void) get_copy(0 /* nullptr */);
-    else
-      break;
+  if (!has_arg()) {
+    warning(WARN_MISSING, "device request expects arguments");
+    skip_line();
+    return;
   }
-  if (('\n' == c) || (EOF == c)) {
-    warning(WARN_MISSING, "device control request expects arguments");
+  if (tok.is_newline() || tok.is_eof()) {
+    warning(WARN_MISSING, "device request expects arguments");
     skip_line();
     return;
   }
+  if ('"' == tok.ch()) {
+    tok.next();
+  }
   macro mac;
   for (;;) {
-    c = get_copy(0 /* nullptr */);
-    if ('"' == c) {
-      c = get_copy(0 /* nullptr */);
-      break;
-    }
-    if (c != ' ' && c != '\t')
+    if (tok.is_newline() || tok.is_eof())
       break;
+    encode_char_for_troff_output(&mac, tok.ch());
+    tok.next();
   }
-  for (; c != '\n' && c != EOF; c = get_copy(0 /* nullptr */))
-    mac.append(c);
   curenv->add_node(new special_node(mac));
-  tok.next();
+  skip_line();
 }
 
 static void device_macro_request()